Built-in self-test circuit

Abstract

A built-in self-test (BIST) circuit is disclosed which integrates the functions of pins for test input data TDI, test output data TDO and an analog input signal VPP into a single digital/analog input/output module, and internally produces a test trigger signal STROBE and a digital-analog conversion signal ANA. In addition, when there is a need to power the test chip with a voltage or current, a data generation circuit of the BIST circuit can generate a digital-analog conversion signal to change an operating mode of the digital/analog input/output module and hence enable the transmission of analog data. According to the present invention, the testing can be performed with only two pins, which leads to an improvement in test efficiency and a reduction in test cost.

What is claimed is: 
     
       1. A built-in self-test (BIST) circuit for testing a test chip, comprising:
 a digital/analog input/output module coupled to the test chip and configured to input digital or analog test input data to the test chip or output digital or analog test output data from the test chip via a first pin; 
 an instruction analysis circuit having a first input terminal for receiving the test input data from the digital/analog input/output module and a second input terminal configured to be coupled to a clock signal via a second pin; and 
 a data generation circuit configured to output a direction control signal and analog-digital conversion data to the digital/analog input/output module based on both the clock signal and a test trigger signal produced by the instruction analysis circuit, the direction control signal configured to instruct the digital/analog input/output module to operate in an input mode or an output mode, the analog-digital conversion data configured to switch the digital/analog input/output module between an analog mode and a digital mode, the data generation circuit further configured to generate the test output data based on a test result from the test chip and output the test output data to the first pin, 
 wherein the BIST circuit does not comprise other pins than the first pin and the second pin. 
 
     
     
       2. The BIST circuit according to  claim 1 , wherein the data generation circuit generates the analog-digital conversion data based on the test trigger signal. 
     
     
       3. The BIST circuit according to  claim 2 , wherein the analog-digital conversion data return to an initial state after predetermined cycles of the clock signal. 
     
     
       4. The BIST circuit according to  claim 1 , wherein the digital/analog input/output module is a bidirectional input/output module. 
     
     
       5. The BIST circuit according to  claim 1 , wherein the data generation circuit is coupled to the test chip and configured to transmit digital data. 
     
     
       6. The BIST circuit according to  claim 5 , wherein the test chip internally produces a test reset signal that is output to the data generation circuit to enable a reset operation.